Abstractly, a graduate employee union gives graduate employees (TAs, RAs, GAs) the ability to work with Penn State to make decisions that affect us as we teach and do research. Practically, a graduate union is a formal organization created by the graduate body and given the legal right to negotiate for them. It negotiates with the university to create a contract that can cover a range of issues: from stipends, health insurance, and workload to safety rules, parking rights, and childcare. Graduate employees elect representatives from among their colleagues to make sure the contract is implemented.
Having a contract and an organization to negotiate it and ensure its implementation means that graduate employees can feel confident knowing that their situation will not radically change year-to-year. It also ensures that they have a formal and impartial process to resolve problems when they arise in the workplace. Many of us have faced instances where we have been overworked or treated unfairly and had no one to turn to. A union can protect us in these times.
It is sometimes thought that a graduate union would have an antagonistic relationship to the university. In fact, a union would work in partnership with the university. The union and the university have a mutual interest in our well-being as students and employees.